The invention relates to a method for setting the tooth face position of a gear wheel, which is non-positively connected to a double-skewed pinion shaft, the use of such pinion shaft in a torque-split spur gear, as well as a spur gear with such pinion shaft.
It is known to assemble pinion shafts, on which a gear wheel with a larger diameter is to be arranged, not from a single component, but rather from several components. The gear wheel can hereby be affixed on the pinion shaft positively or non-positively. In a non-releasable, non-positive connection the gear wheel is initially heated, i.e., thermally expanded, wherein the pinion shaft is cooled. If necessary, a friction coating made, for example, of carborundum is applied on the shaft seat for increasing the friction resistance. The joining process is performed with a joining device, so that the tooth faces of the gear wheel assume a defined position with respect to the tooth faces of the double-skew of the pinion shaft. However, it has been observed in practice, that the required precision is sometimes not obtained. The reasons are not only manufacturing-related deviations of the components to be joined, but also thermally-induced deviations resulting from heating and cooling. Deviations due to manual intervention have also been observed, caused in the assembly process when the components manual joined.
This type of non-positive connections does no longer allow larger corrections of the position of the tooth faces. To attain the required precision, an additional manufacturing process involving grinding of the tooth faces is required. Very large gear wheels may require compensation of deviations of greater than 1 mm. The post-processing is associated with significant costs. Although it is theoretically possible to leave a sizeable amount of overmeasure on the tooth faces, which would reduce the risk that the tooth faces are ground too thin if the gear wheel having an imprecision exceeding the tolerance needed to be ground down further, this approach is uneconomical. Moreover, this approach causes problems with the hardness of the tooth faces, because the previously hardened tooth faces have a limited hardening depth. For this reason, the gear wheel must be very precisely positioned on the pinion shaft in order to minimize post-machining, i.e., grinding.
It is a necessary to exactly position the gear wheel on the pinion shaft, in particular, when the pinion shaft is to be employed in a torque-split spur gear where the two gear wheels of the pinion shafts are in common engagement with a pinion of a driven shaft. If there are deviations in the position of the tooth faces, this multiple engagement may cause an unequal load distribution and hence unequal load carrying characteristics of the teeth, which undesirably increases wear of the gear.